Mediation of exciton concentration on magnetic field effects in NPB : Alq3-based heterojunction OLEDs

Understanding and modulating the spin-pair correlation of conjugated polymer materials in π-conjugated polymer light-emitting devices (PLEDs) plays a crucial role in the development of their applications. We investigated the relationships between the internal hyperfine interactions (HFIs), triplet–triplet annihilation (TTA), and triplet–charge annihilation (TCA) spin evolution processes in π-conjugated PLED. Research has shown that in a unipolar π-conjugated PLED, the “M” shaped ultra-small magnetic field effect is due to the HFI between hole polarons and the spin-mixing process of charge carriers. Under high magnetic fields (15 mT<|B|<350 mT), the TCA process dominates the negative magneto-conductance (MC), and its intensity and sign are not controlled by temperature. In polar π-conjugated PLED, excess carriers can provide conditions for the generation of TCA. Moreover, π-conjugated polymers (emission layers) have relatively strong electron–phonon coupling, which can capture triplet excitons into adjacent organic layers to obtain higher triplet exciton concentrations, resulting in the TTA process. Under low-temperature conditions, excess carriers induce the magneto-electroluminescence (MEL) effect to undergo TTA and form P-type delayed fluorescence. This study can provide a new mechanism explanation for the HFI in PLED devices and a new approach for the effective utilization of triplets.

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Mediation of exciton concentration on magnetic field effects in NPB : Alq3-based heterojunction OLEDs

Abstract: Organic light-emitting diodes (OLEDs) are considered one of the most promising new display technologies owing to their advantages, such as all-solid-state, high color gamut, and wide viewing angle.

Cited by 2 publications

References 42 publications

Molecular design and synthesis of highly soluble hole transporting materials based on phenylnaphthalene cores for solution-processible OLEDs

Molecular design and synthesis of highly soluble hole transporting materials based on phenylnaphthalene cores for solution-processible OLEDs

Effects of unipolar and bipolar charges on the evolution of triplet excitons in π-conjugated PLED

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